|
|
| (One intermediate revision by one other user not shown) |
| Line 1: |
Line 1: |
| {{redirect-distinguish|Dictionary (data structure)|data dictionary}}
| | To most females, BMI calculations may seem a really complicated and complex task which has no hope of learning. However, that is completely untrue considering BMI calculation for females is not certain scientific secret or magic. If you have ever utilized an online BMI calculator for women online, we would recognize by now which when would need you to insert a height plus weight before providing a number because a final output.<br><br>The target fat should nevertheless become the weight based found on the standard BMI height and weight charts. The range presented in the [http://safedietplans.com/bmi-chart bmi chart] is reasonable, and even with muscle and a big body frame, females ought to be capable to reach the healthy range. Moreover, ladies are allowed to be a small heavier as they grow older.<br><br>This system utilizes body fat scales that send a secure small bmi chart men electrical current from the body to calculate the amount of body fat tissue. Your body fat percentage is then calculated based on height, weight, age and sex. It is a harmless system plus very accurate. These scales are accessible in the marketplace and affordable.<br><br>Naturally, children could, plus must, gain fat through the natural task of growth, nevertheless several children go beyond which and place on excess fatty tissue; i.e. they become fat. Obesity is quickly becoming a severe issue with todays youngsters, partially by the wrong nutrition and eating too much of the wrong foods, and partially through ignorance on behalf of the parents that have a misconception which puppy fat is a healthy plus usual thing.<br><br>29. Reading about Running: There are thus many fabulous books out there on running that are fun to read. They can motivate plus excite we. We have a limited posted on the Amazon Store.<br><br>The waist-to-hip ratio is a helpful measure for determining health bmi chart women risk due to the site of fat storage. It is calculated by dividing the ratio of ab girth by hip measuring.<br><br>To ensure all these measurements are accurate, you need to be in .5 a centimeter, or even a .25 centimeter, if possible. Men plus women measure different components of their body.<br><br>Unfortunately far too countless kids have considerably more body fat then that, plus you, because adults plus their parents, are failing them. They will likely not thank us inside years to come for failing them in this method. Dont blame the obese child. Blame the parent, if there is any blame. Some is due to genetics or illness, but just a reasonably very little amount. |
| In [[computer science]], an '''associative array''', '''map''', '''symbol table''', or '''dictionary''' is an [[abstract data type]] composed of a [[Collection (computing)|collection]] of <math>(key, value)</math> pairs, such that each possible key appears at most once in the collection.
| |
| | |
| Operations associated with this data type allow:<ref name="gt">{{citation|contribution=9.1 The Map Abstract Data Type|title=Data Structures & Algorithms in Java|last1=Goodrich|first1=Michael T.|author1-link=Michael T. Goodrich|last2=Tamassia|first2=Roberto|author2-link=Roberto Tamassia|publisher=Wiley|edition=4th|year=2006|pages=368–371}}.</ref><ref name="ms">{{citation|contribution=4 Hash Tables and Associative Arrays|title=Algorithms and Data Structures: The Basic Toolbox|first1=Kurt|last1=Mehlhorn|author1-link=Kurt Mehlhorn|first2=Peter|last2=Sanders|publisher=Springer|year=2008|pages=81–98}}.</ref>
| |
| * the addition of pairs to the collection
| |
| * the removal of pairs from the collection
| |
| * the modification of the values of existing pairs
| |
| * the lookup of the value associated with a particular key
| |
| | |
| The '''dictionary problem''' is the task of designing a [[data structure]] that implements an associative array. A standard solution to the dictionary problem is a [[hash table]]; in some cases it is also possible to solve the problem using directly addressed [[Array data structure|array]]s, [[binary search tree]]s, or other more specialized structures.<ref name="gt"/><ref name="ms"/><ref name="clrs">{{citation | last1 = Cormen | first1 = Thomas H. | author1-link=Thomas H. Cormen | coauthors = [[Charles E. Leiserson|Leiserson, Charles E.]]; [[Ron Rivest|Rivest, Ronald L.]]; [[Clifford Stein|Stein, Clifford]] | title = [[Introduction to Algorithms]] | edition = 2nd | year = 2001 | publisher = [[MIT Press]] and [[McGraw-Hill]] | isbn=0-262-03293-7 | chapter = 11 Hash Tables | pages = 221–252}}.</ref> | |
| | |
| Many programming languages include associative arrays as [[primitive data type]]s, and they are available in [[software library|software libraries]] for many others. [[Content-addressable memory]] is a form of direct hardware-level support for associative arrays.
| |
| | |
| Associative arrays have many applications including such fundamental [[programming pattern]]s as [[memoization]]<!--NOT a misspelling--> and the [[decorator pattern]].<ref name="decorator">{{harvtxt|Goodrich|Tamassia|2006}}, pp. 597–599.</ref>
| |
| | |
| == Operations ==
| |
| In an associative array, the association between a key and a value is often known as a "binding", and the same word "binding" may also be used to refer to the process of creating a new association.
| |
| | |
| The operations that are usually defined for an associative array are:<ref name="gt"/><ref name="ms"/>
| |
| *'''Add''' or '''insert''': add a new <math>(key, value)</math> pair to the collection, binding the new key to its new value. The arguments to this operation are the key and the value.
| |
| * '''Reassign''': replace the value in one of the <math>(key, value)</math> pairs that are already in the collection, binding an old key to a new value. As with an insertion, the arguments to this operation are the key and the value.
| |
| * '''Remove''' or '''delete''': remove a <math>(key, value)</math> pair from the collection, unbinding a given key from its value. The argument to this operation is the key.
| |
| * '''Lookup''': find the value (if any) that is bound to a given key. The argument to this operation is the key, and the value is returned from the operation. If no value is found, some associative array implementations raise an [[Exception handling|exception]].
| |
| | |
| In addition, associative arrays may also include other operations such as determining the number of bindings or constructing an [[iterator]] to loop over all the bindings. Usually, for such an operation, the order in which the bindings are returned may be arbitrary.
| |
| | |
| A [[multimap]] generalizes an associative array by allowing multiple values to be associated with a single key.<ref>{{harvtxt|Goodrich|Tamassia|2006}}, pp. 389–397.</ref> A [[bidirectional map]] is a related abstract data type in which the bindings operate in both directions: each value must be associated with a unique key, and a second lookup operation takes a value as argument and looks up the key associated with that value.
| |
| | |
| ==Example==
| |
| Suppose that the set of loans made by a library is to be represented in a data structure. Each book in a library may be checked out only by a single library patron at a time. However, a single patron may be able to check out multiple books. Therefore, the information about which books are checked out to which patrons may be represented by an associative array, in which the books are the keys and the patrons are the values. For instance (using notation from [[Python (programming language)|Python]], or [[JSON]] (JavaScript Object Notation), in which a binding is represented by placing a colon between the key and the value), the current checkouts may be represented by an associative array
| |
| <source lang="javascript">{ | |
| "Great Expectations": "John",
| |
| "Pride and Prejudice": "Alice",
| |
| "Wuthering Heights": "Alice"
| |
| }</source>
| |
| | |
| A lookup operation with the key "Great Expectations" in this array would return the name of the person who checked out that book, John. If John returns his book, that would cause a deletion operation in the associative array, and if Pat checks out another book, that would cause an insertion operation, leading to a different state:
| |
| <source lang="javascript">{
| |
| "Pride and Prejudice": "Alice",
| |
| "The Brothers Karamazov": "Pat",
| |
| "Wuthering Heights": "Alice"
| |
| }</source>
| |
| In this new state, the same lookup as before, with the key "Great Expectations", would raise an exception, because this key is no longer present in the array.
| |
| | |
| ==Implementation==
| |
| For dictionaries with very small numbers of bindings, it may make sense to implement the dictionary using an [[association list]], a [[linked list]] of bindings. With this implementation, the time to perform the basic dictionary operations is linear in the total number of bindings; however, it is easy to implement and the constant factors in its running time are small.<ref name="gt"/><ref>{{cite web |url=http://www.faqs.org/faqs/lisp-faq/part2/section-2.html
| |
| |title=When should I use a hash table instead of an association list?
| |
| |publisher=lisp-faq/part2
| |
| |date=1996-02-20}}</ref>
| |
| | |
| Another very simple implementation technique, usable when the keys are restricted to a narrow range of integers, is direct addressing into an array: the value for a given key ''k'' is stored at the array cell ''A''[''k''], or if there is no binding for ''k'' then the cell stores a special [[sentinel value]] that indicates the absence of a binding. As well as being simple, this technique is fast: each dictionary operation takes constant time. However, the space requirement for this structure is the size of the entire keyspace, making it impractical unless the keyspace is small.<ref name="clrs" />
| |
| | |
| The most frequently used general purpose implementation of an associative array is with a [[hash table]]: an [[Array data structure|array]] of bindings, together with a [[hash function]] that maps each possible key into an array index. The basic idea of a hash table is that the binding for a given key is stored at the position given by applying the hash function to that key, and that lookup operations are performed by looking at that cell of the array and using the binding found there. However, hash table based dictionaries must be prepared to handle [[Collision (computer science)|collision]]s that occur when two keys are mapped by the hash function to the same index, and many different collision resolution strategies have been developed for dealing with this situation, often based either on [[open addressing]] (looking at a sequence of hash table indices instead of a single index, until finding either the given key or an empty cell) or on [[Hash table#Separate chaining|hash chaining]] (storing a small association list instead of a single binding in each hash table cell).<ref name="gt"/><ref name="ms"/><ref name="clrs"/>
| |
| | |
| Dictionaries may also be stored in [[binary search tree]]s or in data structures specialized to a particular type of keys such as [[radix tree]]s, [[trie]]s, [[Judy array]]s, or [[van Emde Boas tree]]s, but these implementation methods are less efficient than hash tables as well as placing greater restrictions on the types of data that they can handle. The advantages of these alternative structures come from their ability to handle operations beyond the basic ones of an associative array, such as finding the binding whose key is the closest to a queried key, when the query is not itself present in the set of bindings.
| |
| | |
| ==Language support==
| |
| {{main|Comparison of programming languages (mapping)}}
| |
| | |
| Associative arrays can be implemented in any programming language as a package and many language systems provide them as part of their standard library. In some languages, they are not only built into the standard system, but have special syntax, often using array-like subscripting.
| |
| | |
| Built-in syntactic support for associative arrays was introduced by [[SNOBOL]]4, under the name "table". [[MUMPS]] made multi-dimensional associative arrays, optionally persistent, its key data structure. [[SETL]] supported them as one possible implementation of sets and maps. Most modern scripting languages, starting with [[AWK]] and including [[Perl]], [[Tcl]], [[JavaScript]], [[Python (programming language)|Python]], [[Ruby (programming language)|Ruby]], and [[Lua (programming language)|Lua]], support associative arrays as a primary container type. In many more languages, they are available as library functions without special syntax.
| |
| | |
| In [[Smalltalk]], [[Objective-C]], [[.NET Framework|.NET]],<ref>{{cite web |url=http://msdn.microsoft.com/en-us/library/xfhwa508.aspx
| |
| |title=Dictionary<TKey, TValue> Class
| |
| |publisher=MSDN}}</ref> [[Python (programming language)|Python]], and [[REALbasic]] they are called ''dictionaries''; in [[Perl]] and [[Ruby (programming language)|Ruby]] they are called ''hashes''; in [[C++]], [[Java (programming language)|Java]], [[Go (programming language)|Go]], [[Clojure]], [[Scala (programming language)|Scala]], [[OCaml]], [[Haskell (programming language)|Haskell]] they are called ''maps'' (see [[map (C++)]], [[unordered_map (C++)]], and {{Javadoc:SE|java/util|Map}}); in [[Common Lisp]] and [[Windows PowerShell]], they are called ''hash tables'' (since both typically use this implementation). In [[PHP]], all arrays can be associative, except that the keys are limited to integers and strings. In JavaScript (see also [[JSON]]), all objects behave as associative arrays. In Lua, they are called ''tables'', and are used as the primitive building block for all data structures. In [[Visual FoxPro]], they are called ''Collections''.
| |
| | |
| ==See also==
| |
| *[[Tuple]]
| |
| *[[Function (mathematics)]]
| |
| *[[Key-value data store]]
| |
| *[[JSON]]
| |
| | |
| == References ==
| |
| {{Reflist|2}}
| |
| | |
| ==External links==
| |
| {{wiktionary|associative array}}
| |
| * [http://www.nist.gov/dads/HTML/assocarray.html NIST's Dictionary of Algorithms and Data Structures: Associative Array]
| |
| | |
| {{Data structures}}
| |
| {{Data types}}
| |
| | |
| <!--Categories-->
| |
| [[Category:Associative arrays|*]]
| |
| [[Category:Abstract data types]]
| |
| [[Category:Composite data types]]
| |
| [[Category:Data types]]
| |
To most females, BMI calculations may seem a really complicated and complex task which has no hope of learning. However, that is completely untrue considering BMI calculation for females is not certain scientific secret or magic. If you have ever utilized an online BMI calculator for women online, we would recognize by now which when would need you to insert a height plus weight before providing a number because a final output.
The target fat should nevertheless become the weight based found on the standard BMI height and weight charts. The range presented in the bmi chart is reasonable, and even with muscle and a big body frame, females ought to be capable to reach the healthy range. Moreover, ladies are allowed to be a small heavier as they grow older.
This system utilizes body fat scales that send a secure small bmi chart men electrical current from the body to calculate the amount of body fat tissue. Your body fat percentage is then calculated based on height, weight, age and sex. It is a harmless system plus very accurate. These scales are accessible in the marketplace and affordable.
Naturally, children could, plus must, gain fat through the natural task of growth, nevertheless several children go beyond which and place on excess fatty tissue; i.e. they become fat. Obesity is quickly becoming a severe issue with todays youngsters, partially by the wrong nutrition and eating too much of the wrong foods, and partially through ignorance on behalf of the parents that have a misconception which puppy fat is a healthy plus usual thing.
29. Reading about Running: There are thus many fabulous books out there on running that are fun to read. They can motivate plus excite we. We have a limited posted on the Amazon Store.
The waist-to-hip ratio is a helpful measure for determining health bmi chart women risk due to the site of fat storage. It is calculated by dividing the ratio of ab girth by hip measuring.
To ensure all these measurements are accurate, you need to be in .5 a centimeter, or even a .25 centimeter, if possible. Men plus women measure different components of their body.
Unfortunately far too countless kids have considerably more body fat then that, plus you, because adults plus their parents, are failing them. They will likely not thank us inside years to come for failing them in this method. Dont blame the obese child. Blame the parent, if there is any blame. Some is due to genetics or illness, but just a reasonably very little amount.